PROJECT SUMMARY The epithelium that lines the airway comprises a variety of specialized cell types that play essential roles in lung health. Changes in the epithelium are prominent features of asthma and other common lung diseases. During normal differentiation, dramatic changes in gene expression are required for the development of the unique functional capabilities of the basal, secretory, and ciliated cell populations within the epithelium. Furthermore, in airway disease, each cell type has distinctive gene expression changes in response to pathogenic cytokines. Over the past two decades, we have used transgenic mouse modeling, human cell culture, and clinical studies to identify molecular mechanisms that underlie changes in epithelial gene expression that contribute to airway obstruction in asthma. Although we and others have gained tremendous insights from mouse models, our overall goal of understanding the biology underlying asthma and other human airway diseases has increasingly led us to focus on developing appropriate human experimental systems. In the past several years, we and our collaborators have developed a set of powerful approaches including single cell RNA-seq, ChIP-seq, massively parallel reporter assays, and CRISPR-mediated gene editing, to address mechanistic questions in primary human airway epithelial cells. These approaches now enable us to perform potentially groundbreaking experiments that give new insights into airway epithelial cell complexity, identify key regulators of gene expression and epithelial cell function, and reveal how specific airway epithelial gene regulators contribute to asthma and other airway diseases. Most disease-associated genetic variants are found in regulatory regions, and our work has important implications for understanding genetic contributions to airway disease risk. We will also work to apply insights about gene regulation to develop approaches for therapeutic reprogramming of the epithelium to prevent, cure, or treat disease. The environment at UCSF provides access to creative collaborators, cutting-edge technologies, and key clinical resources and affords outstanding opportunities for working with early career investigators who will be well positioned to continue to move the field forward.